 /*******************************************************************************
  * Copyright (c) 2000, 2004 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.runtime;

 /**
  * <code>Assert</code> is useful for for embedding runtime sanity checks
  * in code.
  * The predicate methods all test a condition and throw some
  * type of unchecked exception if the condition does not hold.
  * <p>
  * Assertion failure exceptions, like most runtime exceptions, are
  * thrown when something is misbehaving. Assertion failures are invariably
  * unspecified behavior; consequently, clients should never rely on
  * these being thrown (and certainly should not being catching them
  * specifically).
  * </p>
  */
 public final class Assert {
     /* This class is not intended to be instantiated. */
     private Assert() {
         // not allowed
 }

     /** Asserts that an argument is legal. If the given boolean is
      * not <code>true</code>, an <code>IllegalArgumentException</code>
      * is thrown.
      *
      * @param expression the outcode of the check
      * @return <code>true</code> if the check passes (does not return
      * if the check fails)
      * @exception IllegalArgumentException if the legality test failed
      */
     public static boolean isLegal(boolean expression) {
         return isLegal(expression, ""); //$NON-NLS-1$
 }

     /** Asserts that an argument is legal. If the given boolean is
      * not <code>true</code>, an <code>IllegalArgumentException</code>
      * is thrown.
      * The given message is included in that exception, to aid debugging.
      *
      * @param expression the outcode of the check
      * @param message the message to include in the exception
      * @return <code>true</code> if the check passes (does not return
      * if the check fails)
      * @exception IllegalArgumentException if the legality test failed
      */
     public static boolean isLegal(boolean expression, String message) {
         if (!expression)
             throw new IllegalArgumentException (message);
         return expression;
     }

     /** Asserts that the given object is not <code>null</code>. If this
      * is not the case, some kind of unchecked exception is thrown.
      *
      * @param object the value to test
      * @exception IllegalArgumentException if the object is <code>null</code>
      */
     public static void isNotNull(Object object) {
         isNotNull(object, ""); //$NON-NLS-1$
 }

     /** Asserts that the given object is not <code>null</code>. If this
      * is not the case, some kind of unchecked exception is thrown.
      * The given message is included in that exception, to aid debugging.
      *
      * @param object the value to test
      * @param message the message to include in the exception
      * @exception IllegalArgumentException if the object is <code>null</code>
      */
     public static void isNotNull(Object object, String message) {
         if (object == null)
             throw new AssertionFailedException("null argument:" + message); //$NON-NLS-1$
 }

     /** Asserts that the given boolean is <code>true</code>. If this
      * is not the case, some kind of unchecked exception is thrown.
      *
      * @param expression the outcode of the check
      * @return <code>true</code> if the check passes (does not return
      * if the check fails)
      */
     public static boolean isTrue(boolean expression) {
         return isTrue(expression, ""); //$NON-NLS-1$
 }

     /** Asserts that the given boolean is <code>true</code>. If this
      * is not the case, some kind of unchecked exception is thrown.
      * The given message is included in that exception, to aid debugging.
      *
      * @param expression the outcode of the check
      * @param message the message to include in the exception
      * @return <code>true</code> if the check passes (does not return
      * if the check fails)
      */
     public static boolean isTrue(boolean expression, String message) {
         if (!expression)
             throw new AssertionFailedException("assertion failed: " + message); //$NON-NLS-1$
 return expression;
     }
 }

